3D Basin and Petroleum Systems Modeling Offshore Brazil: A Large-Scale Regional Model of the ‘Greater Campos Basin’
Hans Axel Kemna1, David J. Curry2, and Marcio Rocha Mello3
1Ucon Geoconsulting, Moritzstr. 18, D-47803 Krefeld, Germany
2Devon Energy Corporation, 1200 Smith Street, Houston, Texas 77002 USA
3HRT Petroleum, Av. Atlantica 1130, Copacabana, Rio de Janeiro, RJ, Brazil
Basin and petroleum systems models are currently increasingly used for risk assessment at block and prospect scale. This study is intended to demonstrate the benefit of large-scale, regional models, even in highly explored areas such as the Brazilian shelf. Understanding the evolution of a basin and petroleum province on a wider spatial scale and incorporating and integrating all relevant geologic data is mandatory for strategic and exploration purposes.
A fully calibrated pressure/temperature and petroleum generation/expulsion/migration model has been built that covers much of the Santos, Campos, and Espirito Santo Basins (Fig. 1). This area has informally been termed the ‘Greater Campos Basin’. This model, approximately 1200 km by 200 km in size, incorporates a detailed salt restoration, full maturity/temperature calibration using an extensive well data base, calibration of known accumulations including PVT conditions and hydrocarbon compositions, use of multi-component generation and cracking kinetics. All significant source intervals (e.g., the Talc Stevensite and Coquinas intervals in the Cretaceous pre-salt Lagoa Feia unit) and reservoir units are included in the model.
Simulations show that the temperature history of the Greater Campos Basin is highly complex, and that the timing of expulsion ranges from Albian to present day. In many areas the thermal effects of increased burial did not keep pace with the post-rift decay in heat flow and the impact of salt diapirism on the thermal history of the pre-salt layers in the Santos basin, thus leading to temperatures having decreased steadily in the last 80 Ma. The complexity and variability of the thermal histories in the model area, lead to a range of key risks in different parts of the basin for both pre-salt and post-salt plays, ranging from severe biodegradation to extensive thermal cracking of reservoired hydrocarbons.
The regional model of the Greater Campos Basin demonstrates the importance of large scale basin modeling in exploration:
• Integration of a broad range of geological data to build an understanding of the basin evolution, including source occurrence, reservoir deposition, and regional variability
• Identification of the key processes that control the hydrocarbon occurrences and fluid properties in different parts of the basin
• Delineation of the extent of different plays within an area, based on the variability in these key processes.
• Identification of ‘hidden’ or over-looked plays that may not be immediately apparent from smaller scale, block-based models
• Identification of the important uncertainties and scenario-testing to define their limits
• Provide a regional integration framework for more detailed modeling of areas of possibly prospective areas.
Modeling the Greater Campos Basin in one regional study has provided regional understanding of the variability of this highly complex petroleum province. The study will support long-term strategic business decisions by identifying regional key risks of the Santos, Campos and Espirito Santo Basins.
AAPG Search and Discovery Article #90091©2009 AAPG Hedberg Research Conference, May 3-7, 2009 - Napa, California, U.S.A.